Holocene Hunter-Gatherers of the Lower Ohio River Valley

2. Physical Landscape

2 / Physical Landscape Introduction The first hunter-gatherers to enter the Lower Ohio Valley encountered a world unmodified by human activity. The physical landscape consisted of a variety of environmental features that included climate, landforms, plants, animals, mineral and lithic resources, and water. At the time the first hunter-gatherers arrived, their physical world was strongly influenced by the retreating Pleistocene glacier. Over time, the climate gradually ameliorated with Holocene environmental conditions becoming more prevalent. Changes in the kind, number, and distribution of the region’s natural resources created new opportunities for people to make choices about how to best respond to those changes. Today, most people would agree that the environment did not determine the nature of these societies; however, the distribution and frequency of the region’s natural resources did influence where people lived, what they did there, and how long they stayed. As hunter-gatherers spread across the Lower Ohio Valley landscape, they gradually modified their physical world, creating a cultural landscape that reflected their particular cultural preferences and beliefs. The Lower Ohio Valley’s cultural landscape continued to evolve throughout the period covered by this book (and long after) as its Native American inhabitants slowly changed the physical landscape into a place that reflected their technological , social, and ideological worlds. If we are to understand how hunter-gatherers created their cultural landscape , we need to know about the physical world in which they lived and how Physical Landscape / 13 it varied temporally and spatially. This chapter discusses the character of the late Pleistocene and Holocene environments, drawing on information from geology , geography, paleoecology, and the historical record. Landforms and Topography The Ohio River flows south and southwest for nearly 1,600 km before joining the Mississippi River at Cairo, Illinois, making it the one of the longest rivers in eastern North America. Although shorter than the Mississippi River, at their confluence, the Ohio typically carries a much greater volume of water than does the Mississippi.The Ohio River system (including theTennessee and Cumberland rivers) drains nearly 520,000 km2 of eastern North America, including parts of New York, Pennsylvania, Maryland, North Carolina, Ohio, West Virginia, Kentucky, Indiana, Illinois, Tennessee, Virginia, Georgia, Alabama , and Mississippi (U.S. Fish and Wildlife Service 1999). The Ohio River basin is often subdivided into three units based on its physiographic variability.The eastern portion lies within the Appalachian Plateau . The region’s rugged topography is largely attributable to the erosion of thick beds of sandstone and shale. The Central Lowlands comprise the basin’s middle one-third. Its flat to slightly rolling topography was created by repeated Pleistocene glaciation. Finally, the Lower Ohio River valley, comprising the western one-third of the river, is dominated by sandstone and limestone formations of the Interior Low Plateau province. A small area of the Gulf Coastal Plain province is located near the confluence of the Ohio and Mississippi rivers (U.S. Fish and Wildlife Service 1999). For much of its course, the Lower Ohio River flows along the northern edge of the Interior Low Plateau. Bedrock geological formations, consisting of thick beds of Mississippian and Pennsylvanian limestone, sandstone, and shale, underlie the river, dipping gently to the northwest from the Appalachian highlands in the east to the coal basin of western Kentucky, Indiana, and Illinois in the west (Fenneman 1938:411–413). Much of the bedrock valley floor lies below deep deposits of alluvial and glacial clays, sands, and gravels of Holocene or Pleistocene age. Bedrock is exposed only where the river flows against the valley wall, and at the Falls of the Ohio River (Powell 1999:9). Geological processes that spanned millions of years created the landscape of the Lower Ohio Valley. Between the Falls of the Ohio and the Mississippi River, the Ohio flows through at least four major physiographic regions containing geological formations dating from the Ordovician (ca. 490 million 14 / Physical Landscape years ago) to the Quaternary (ca. less than one million years ago) geological periods (McGrain 1983:Figures 9 and 10) (Figure 2.1). Pleistocene glaciers and their melt waters shaped or modified many of the valley’s river and stream channels . In addition, thick layers of windblown glacial silt, known as loess, cap ridgetops and hilltops throughout the western part of the region. The Falls of the Ohio River, located at Louisville, Kentucky, was perhaps the most impressive natural feature of the Lower Ohio River (Figure...